This invention relates to a magneto-optical disk device using a magneto-optical disk cartridge.
The magneto-optical disk device is a memory device having large memory capacities as is the conventional write once optical disk device, and can perform rewriting and erasure of information the conventional write once optical disk device cannot do. Recently various products of magneto-optical disk devices are available. The magneto-optical disk technology is about to reach the production stage, leaving the experimental stage.
In accordance with such development of the magneto-optical disk technology, ISO (International Standardization Organization) standards of the magneto-optical disk was reviewed, and ISO standards for the 130 mm (5.25 inch)-disk cartridge were established.
The 5-inch magneto-optical disk cartridge is easy to replace the disk, and is easy to handle because its recording surface is protected. The cartridge can have a recording capacity hundreds times that of the high density-floppy disk although the cartridge is small-sized. Thus, the 5-inch magneto-optical disk is expected to dominate the future magneto-optical disk medium.
Thus, the magneto-optical disk is much expected to be a large-capacity memory device for the next generation. But a problem with the magneto-optical disk is that much time is taken to read and write data because the device has a large number of tracks and deals with a large volume of data. Accordingly it is a very significant technical problem with the magneto-optical disk device how to record and reproduce a large volume of data at high speed.
To record and reproduce a large volume of data at high speed it can be proposed to rotate the magneto-optical disk at higher speed. But in view of the mechanical properties of the actuator it is difficult to rotate the magneto-optical disk at a high speed more than two times the conventional speed. What is desired is to increase a number of the magneto-optical head for reading and writing data. But the standardized magneto-optical disk cartridge has one head window for one magneto-optical head. It is structurally very difficult to accommodate a plurality of large magneto-optical heads in the small head window.
The magneto-optical disk device has a very large number of tracks and a narrow track pitch. Accordingly tracking servo drive of very high precision is necessary.